In recent years, an optical-magnetic hybrid recording technology in which optical recording and magnetic recording are combined with each other has been proposed as one of technologies for improving a recording density of a magnetic disk device. This technology adopts a method of heating, at the time of recording, a medium at the same time as generation of an applied magnetic field to thereby reduce a retention force of the medium. The adoption of this method makes it possible to facilitate recording into a recording medium having such a high retention force that recording by a conventional magnetic head is difficult due to an insufficient recording magnetic field intensity. On the other hand, for reproduction, a magnetoresistance effect used in conventional magnetic recording is utilized.
This hybrid recording method is referred to as thermally assisted magnetic recording. Here, a method of using a near field has been proposed as a heat method using light. In the thermally assisted magnetic recording using a near field, laser light generated by a laser light source is guided to a recording head, and a light spot diameter is converted into a size and a shape which is suitable for recording, by using an element having a function of generating near field light. Hereinafter, the element having the function of generating near field light as described above is referred to as a near field light generation element.
Normally, for the necessity of using the laser light source inside of a package of a disk drive, a small-sized semiconductor laser (LD: Laser Diode) with low power consumption is used among laser light sources. When the laser light source is used in a thermally assisted magnetic recording device using a near field which realizes a recording density of Tb/in2 or more, a power of approximately several mW is required before a recording medium surface is reached.
Optical components which guide the laser light generated by the semiconductor laser to the near field generation element include a reflection mirror, a lens, and an optical waveguide. The light generated by the semiconductor laser passes through the optical components and the near field generation element placed in an optical path, and reaches a recording medium. The light intensity of the laser light decreases while passing through the optical path, and becomes several tens of percent of an output of the light generated by the semiconductor laser. Main causes of the decrease in light intensity include: absorption loss and scattering loss when the light passes through the optical components; coupling loss resulting from deviation from an ideal position which occurs at the time of mounting or adhesion of the optical components and at the time of soldering; and the like. Accordingly, in the thermally assisted magnetic recording, a structure in which the coupling loss occurring until the light enters the near field generation element is reduced is essential.
Meanwhile, downsizing of a slider of a magnetic disk is advancing. For example, at present, a femto slider having a size of 0.85 mm×0.7 mm×0.23 mm is becoming mainstream. In addition, a distance between a floating surface (ABS: Air Bearing Surface) and a disk has reached as small as approximately 10 nm. The downsizing thereof will further advance thereafter, and the floating amount is expected to become smaller. However, in the case of the further advance in downsizing and the smaller floating amount, it is predicted that warpage of the slider itself will become a big problem. In addition, in order to reduce loss of the laser light, it is effective to place the semiconductor laser in the vicinity of the slider. However, it is known that, because the semiconductor laser itself becomes a heat source, if uniform heat radiation to the slider is not possible, deformation of the slider due to the heat is accelerated, and the lifetime of the semiconductor laser is degraded. Therefore, a structure in which the heat is radiated to the slider with high efficiency is essential. As described above, realization of the thermally assisted magnetic recording head is expected to essentially require not only the structure in which the coupling loss is reduced by the decrease in position deviation but also the mounting structure in which the heat can be radiated to the slider with high efficiency while suppressing the warpage of the slider.
It should be noted that Patent Literature 1 discloses a fixing method in which a heat curing adhesive and a UV adhesive are used for fixing a slider and a flexure to each other, and fluctuations in attachment dimensions are thus reduced, whereby enhancement in accuracy is achieved. In addition, Patent Literature 2 discloses a magnetic head in which an adhesive having both properties of light curing and heat curing is applied to a joint portion between a slider and a flexure, and a heat curing adhesive and a conductive adhesive for electrical conduction are applied to a region other than an application region of the adhesive, whereby the adhesion strength between the slider and the flexure is enhanced. In addition, Patent Literature 3 discloses a thermally assisted magnetic head in which a concave surface is formed in at least part of an adhesion surface of a light source support substrate to be adhered to a slider, whereby a position of a light source can be adjusted with high accuracy.